The atlantic forest in São Paulo state, has been described in the scientific literature as having high floristic diversity. Such statement is based on data and conclusions of local floristic and phytosociological studies. However, the studies supporting this idea seldom give a clear definition of the plant group analysed, the scale of the study, nor, most significantly, the forests used for comparisons. Here we compare woody species richness data (³ 2.5 cm dbh)from the atlantic forest in São Paulo to similar data from other neotropical forests. Thereafter, we discuss the major relationships between historical and ecological processes and woody species richness in neotropical forests. Neither data on woody species richness nor characteristics of latitude, altitude, rainfall and soil in the atlantic region is able to support the idea of high woody species richness in the São Paulo atlantic forest. Studies using comparable data sets are required in order to characterise woody species richness in all types of the atlantic forest, as well as to suggest the mechanisms responsible for plant richness in different scales.